Process of splitting off sulpho groups from anthraquinone sulphonic acid derivatives



Patented Nov. 22, 1927.

UNITED STATES nonnnr murmur. scmnm, or nnnnnrnnn, mznsrurr coaronn'rxon, or ew Your. n.

ULPHO GROUPS, FROM AHTHRAQUIHONE SULPHOHIG ACID DERIVATIVES.

PROCESS OF BPLIT'I'ING OFF 8 GEBIANY, ASSIGNOB TO GBASBELLI Y., A CORPORATION OF DELAWARE.

Io Drawing. Application fled Augult 3, 1828, serial No. 126,989, and in Austria April 8, 1926.

The present invention relates to the use of particular alkaline agents for splittin ofi sulpho oups from anthraquinone sulp onic acid hy compounds.

I' have shown in my application Serial No. 101,780 filed April 13, 1926, that anthrauinone sulphonic acid derivatives; i. e., hyroxy, amino and arylamino substituted anthraquinone sulphomc acids can be reduced 10 in slightly acid, neutral or weakly alkaline solutions to hydro compounds. These hydro compounds, when treated with alkaline agents, such as dilute caustic soda, potassium or sodium carbonate solutions, etc., loose a l sulpho group which is eliminated in form of sul hurous acid.

have now found that pyridine bases, and especially yridine itsel are particularly suited alka ine agents to achieve this elimination of a sulpho group from anthraquinone sulphonic acid hydro compounds.

The hydro compounds, in contradistinction to the leuco compounds, are not reverted to the parent material by oxydation. Their structural formula is not exactly known, but

as a mere illustration in the presentinvention, a formula of the following type might be assumed:

If a pyridine base is added to an aqueous solution of such a'hydro compound and the solution heated sulphurous acid is split off 40 andi an anthraquinone type compound recovere It is, however, not necessary to prepare and isolate the hydro compound in substances.

If pyridine is added to the solution obtained by reducing an anthraquinone sulphonic acid derivative in slightly acid, neutral or weakly alkaline solution, or by carrying out the reduction directl in a solution containing pyridine and heating afterwards,

the resulphonated antbraquinone compoun are obtained very easily and with excellent purity and yields.

I wish it to be understood that the term anthraquinone sulphonic acid derivative as used herein is meant to comprise such anthraquinone sulphonic acids as contain at least one of the groups hydroxy, amino, or alkylamino or several like or different of the above mentioned substituents.

The following example will further illustrate m invention, the parts being by weight, ut I wish it to be understood that my invention is not limited to the particular substances, nor to the exact reaction conditions mentioned herein. I

Ewample 1.-10 parts p-diamino-anthrarufin monosulphonic acid of the formula:

NH: (I 0H Dan 0 I H O are dissolved in 1000 parts water, containing 150 parts of p ridine. The solution is heated to 85-90 and to the blue solution obtained one adds 10 parts sodium hydosulphite. The color of the solution turns red, due to the formation of the hydro compound. On continued heating crystalline needles start to separate and when the solution has become practically colorless the preci itate is filtered ofl, washed with water and 'ed. It represents practically pure para-diaminoanthrarufin.

Emample 2.--10 parts p-diamino-anthrarufin-disulphonic acid are dissolved in 850 parts water and 150 parts pyridine and the solution heated on the water bath to about 8590 C. 12 parts sodium hydrosulphite are then added in small portions, subsequent portions only being added after the preceding one has reacted and the hydro compound formed lost its sulpho group. When about half of the hydrosulphite has been added crystals of p-diamino-anthrarufin start to separate. The solution should have only a violetish or faint reddish tint after all of the hydrosulphite has been added. The -di amino-anthrarufin formed is then filtere 05,

ds washed and dried. It is obtained exceeding- 1y pure and with an excellent yield.

his applicatlon is a continuation in part of as application Serial No. 101,780, filed Ali" 13, 1926.

claim 1. In proceses of splitting 01f sulpho groups from anthraquinone sulphonic acid erivatives the step which consists in heating the h dro compounds thereof in the presence 0 a pyridine basei 2. In processes of splitting ofi sulpho oups from anthra uinone sulphonic acid erivatives the step w ich consists in heating the hydro compounds thereof in the presence of pyridine.

3. Proce$of splittin ofi sulpho groups from anthraquinone sui phonic acid derivatives which comprises reducing such derivatives to their corresponding hydro comunds in the presence of a. p ridine base and heating the resulting reaction rmxture.

4. Process of splitting off sulpho groups from anthraquinone sulphonic acid derivatives which comprises reducing such derivatives to their correspondin hydro comounds in the presence of pyridine and heatmg the resulting reaction mixture. I

5. Process of splittin ofl sulpho roups from anthraquinone su plhonic acid erivatives which comprises eating a solution thereof in the presence of apyridine base and a reducing agent.

6. Process of splitting ofisulpho oups from anthraquinone sul honic acid ggrivatives which 'comprises ieating a solution thereof in the presence of pyridine and 'a reducing agent.

In testimony whereof, I aflix my signature.

ROBERT EMANUEL SCHMIDT.

of to application Serial No. 101580, filed Apri 13, 1926.

I claim 1. In processes of splitting oil sulpho oups from anthraquinone sulphonic acid erivatives the step which consists in heating the h dro compounds thereof in the presence 0 a. pyridine base.

2. In processes of splitting oif sulpho cups from anthra uinone sulphonic acid erivatives the step w ich consists in heating the hydro compounds thereof in the presence of pyridine.

3. Process of splitting off sulpho groups from anthraquinone sulphonic acid derivatives which comprises reducing such derivatives to their corresponding hydro compounds in the presence of a, p ridine base and heating the resulting reaction mixture.

4. Process of splitting ofi' sulpho groups from anthraquinone sulphonic acid derivatives which comprises reducing such derivatives to their corresponding hydro coinpounds in the presence of pyridine and heating the resulting reaction mixture.

5. Process of splitting off sulpho groups from anthraquinone sul honic acid derivatives which comprises heating a solution thereof in the presence of a pyridine base and a reducing agent.

6. Process of splitting oil sulpho 'roups from anthraquinone sulphonic acid erivatires which 'oomprises heating a solution thereof in the presence of pyridine and a reducing agent.

in testnnony whereof, I affix my signature.

ROBERT EMANUEL SCHMIDT.

QERTIFEQATE OF (IURRECTION.

Patent No. 1, 650,158.

Granted November 22, 1927, to

RGBER? EMANUEL SCHMIDT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 51, for the word "resuiphonated" read "desuiphonated"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 27th day of December, A. D. 1927.

Seal.

M. J. Moore, Acting Commissioner of Patents.

CERTIFECATE OF CORRECTION.

Patent No. 1,650, E58. Granted November 22, 1927, to

ROBERT EMANUEL SCHMIDT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 51, for the word "resuiphonated" read "desulphonated"; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 27th day of December, A. D. 1927.

M. J. Moore, Seal. Acting Commissioner of Patents. 

